Chapter 12 — Integrated Economic Analysis Studio

Core question

Can you move from a real problem to a model, mechanism, calculation, evidence check, and defensible policy judgment?

Learning outcomes

You will be able to:

• select and combine models without treating any one model as reality;
• distinguish an accounting result, model prediction, empirical estimate, and value judgment;
• evaluate policy through efficiency, distribution, stability, and implementation;
• write a compact economic argument whose limits are explicit.

1. Select the smallest model that answers the question

Using more diagrams does not make an answer stronger. Every added model must resolve a question the previous one could not.

2. The eight-sentence discipline

A compact analysis can follow eight moves:

1. define the outcome and time horizon;
2. state the baseline or counterfactual;
3. name the shock or intervention;
4. choose the model and assumptions;
5. trace the mechanism;
6. calculate or sign the main effects;
7. compare the prediction with evidence;
8. judge the policy and name the uncertainty that could reverse the judgment.

3. Case A — a sugary-drink tax

The decision

A city is considering a tax of £2 per unit on sugary drinks. Before tax:

Equilibrium is P = £4, Q = 60. With P_b - P_s = £2:

so P_b = £5, P_s = £3, and Q = 50.

The equal split comes from these particular slopes. The statutory payer does not determine economic incidence.

Add the policy objective

If consumption imposes health costs not considered by buyers and sellers, the market quantity can exceed the social optimum. A corrective tax can improve efficiency by aligning private and social marginal cost. But four questions remain:

1. How large is the external cost?
2. Do consumers substitute toward other high-sugar products?
3. Who bears the burden by income and health status?
4. How is the revenue used?

Check against evidence

A systematic review and meta-analysis covering 86 studies reported average tax pass-through of 82% and a 15% reduction in sugary-drink sales, with substantial heterogeneity across designs and settings (Andreyeva et al., 2022).

That evidence supports a price-and-quantity mechanism. It does not reveal this city's exact response, long-run health gain, distributional effect, or optimal tax rate.

Policy judgment

A defensible recommendation might combine the tax with free drinking water, nutrition support, transparent use of revenue, and pre-specified evaluation of prices, sales, substitution, and outcomes by income group. This follows from the mechanism; it is not implied by the tax diagram alone.

4. Case B — energy inflation in an importing economy

Initial shock

World energy prices rise 40% and the domestic currency depreciates 10% against the invoicing currency:

Suppose energy has a 10% CPI weight and 70% of the combined cost reaches consumers. A first-round arithmetic contribution to the price level is:

or about 3.8%. This is not automatically a permanent 3.8 percentage-point addition to annual inflation: weights, timing, substitution, taxes, caps, and indirect effects matter.

Trace the whole system

Diagnose before prescribing

Bernanke and Blanchard's decomposition of US pandemic-era inflation attributes the initial surge mainly to commodity and sectoral price shocks, with labour-market tightness becoming more important for persistence. The lesson is to separate the source of an inflation increase from the mechanism that keeps it going (Bernanke & Blanchard, 2023).

Their evidence concerns the United States and a specific episode. An energy-importing economy with currency depreciation, weaker credibility, or regulated prices may transmit the shock differently.

A coherent package

One possible package is temporary targeted income support, preservation of marginal energy prices, credible monetary communication focused on persistence, bank stress monitoring, and accelerated high-return energy investment. The recommendation is conditional on stable expectations, administrative capacity, and debt space; change those conditions and the package should change.

5. Compare the cases

The common method is unchanged: define the counterfactual, trace behaviour, quantify where possible, inspect distribution, and state what evidence could overturn the result.

6. Turn analysis into a paragraph

Weak:

Energy inflation shifts supply and the government should intervene.

Stronger:

A rise in the domestic-currency cost of imported gas raises firms' marginal costs, shifting short-run aggregate supply left; output falls while the price level rises. A universal price cap can protect current purchasing power but weakens conservation and exposes the budget to the wholesale price. Targeted lump-sum support preserves the marginal price signal, although its value depends on administrative reach. I would therefore target temporary transfers and review them when wholesale prices or household arrears cross pre-announced thresholds.

The second paragraph names the shock, model, mechanism, trade-off, recommendation, and exit condition.

7. Capstone task

Choose one current economic claim and submit a 1,200-word policy note:

1. a one-sentence question and explicit counterfactual;
2. one diagram or balance sheet;
3. one transparent calculation;
4. two primary or peer-reviewed sources;
5. mechanism and distributional analysis;
6. recommendation, implementation risk, and falsification condition.

8. Evidence trail for further study

Final check

• What is the counterfactual?
• Which statement is identity, theory, estimate, or judgment?
• Which assumption drives the result?
• Who gains, who loses, and when?
• What observation would change the conclusion?

If your answer makes those five items visible, you are doing economics rather than reciting it.